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Saturday, September 24, 2011

NASA's Upper Atmosphere Research Satellite fell back to Earth between 11:23 p.m. ET Friday, Sept. 23 and 1:09 a.m. ET Sept. 24. The Joint Space Operations Center at Vandenberg Air Force Base in California said the satellite fell out of orbit over the Pacific Ocean. The precise re-entry time and location are not yet known with certainty. NASA will hold a press teleconference today at 2 pm ET to discuss the re-entry of UARS. Here is the link http://www.nasa.gov/news/media/newsaudio/index.html

Neptune was discovered one Neptune year ago. On September 23, 1846 Neptune was seen near its predicted location, with the discovery credited to Johann Galle, John Couch Adams, and Urbain Le Verrier. On Jul 7, 2011 Neptune completed its first orbit around the Sun since that day. Neptune is far from the Sun and very cold. I wonder if you would worry about Space Weather if you lived on (or floated in the clouds of) Neptune?

Friday, September 23, 2011

Today is the autumnal equinox, the first day of fall. Thanks to the increased solar activity of Solar Cycle 24, the UARS satellite will re-enter this afternoon. As it re-enters it will break up into a large number of pieces, some of which may make it to the ground.

Thursday, September 22, 2011

An active region is rotating into view on the Sun's limb. This morning it let loose with a X1.4 flare. Let's hope for more as the active region continues to rotate onto the disk. I like the way the tops of the loops saturate and bloom while the loops remain visible. A little bit of spray at 11:02:34, but if a prominence eruption also happened it was before the flare started.

Friday, September 16, 2011

According to the drawings at the Solar Influences Data Analysis Center SIDC, September 16, 2011 had a sunspot number of 194. That's 74 spots and 12 groups. Looks good in the magnetic field from HMI as well. Still on track for a below average sunspot number for Solar Cycle 24, but we are seeing some good activity now.

Sunday, September 11, 2011

The Fall 2011 eclipse season started today. Here is an AIA 171 image from 0657 UT with the first eclipse! SDO has eclipse seasons twice a year near each equinox. For three weeks near midnight Las Cruces time (about 0700 UT) our orbit has the Earth pass between SDO and the Sun. These eclipses can last up to 72 minutes in the middle of an eclipse season. The current eclipse season started on September 11 and lasts until October 4. The continuous contact with the ground station our orbit allows was judged to outweigh the loss of some images.

Thursday, September 1, 2011

On September 1, 1859 Richard Carrington observed a solar flare while drawing sunspots. Rather than look at the same drawing of sunspots that we always see, let's look at the magnetometer records released this year by the British Geological Survey (see "Search the Collection" at this link.) Magnetometers measure the strength and direction of the Earth's magnetic field. BGS scanned and released the records from several stations, including the Greenwich station we show here.

On the top is the day of the flare. In the oval in the upper right is the effect of the solar flare at 11:18 am. (Perhaps you can figure out the times in these plots!) Other than a few small changes, the traces on 9/1/1859 look pretty smooth.

A coronal mass ejection, a large surge of particles from the Sun, often comes with a flare. In the lower plot are the traces from two days later, while the particles ejected from the Sun at the same time as the 9/1/1859 flare are hitting the Earth's magnetosphere. The traces cover the page, with many rapid changes. People started associating flares on the Sun with the changes in the magnetic field being measured by the magnetometers.

This was not just scientific curiosity. Those changes in the magnetic field affected the telegraph system, shocking the operators and allowing them to send messages without batteries while the aurora caused by the solar storm pulsed overhead.

Today we watch the Sun for signs of flares and coronal mass ejections with SDO and other satellites. We monitor the Earth's magnetic field at stations of the BGS and other organizations. Space weather continues to affect our lives when it disrupts radio communications just like it disrupted telegraphs in early September, 1859.

This anniversary was celebrated on The Writer's Almanac, along with a poem about watching a James Bond movie.